Roll for marking metal strip



13, 1964 G. A. BARTHOLOMEW ETAL 3,152,977

ROLL FOR MARKING METAL STRIP 2 Sheets-Sheet 1 Filed Dec. 8. 1960 IN VE N TORS GEORGE A. BAR THOL OMEW and 552 "if By A Horney 1964 s. A. BARTHOLOMEW ETAI. 3, 7

ROLL FOR MARKING METAL STRIP 2 Sheets-Sheet 2 Filed Dec. 8. 1960 m EEI N N k N 3 m .3 I .QN

INVENTORS GEORGE A. BARTHOLOMEW and RICHARD E HIGGS 8y I 9 Attorney ode andthe strip contacting the roll is the anode.

when the sleeve-covered roll contacts the traveling strip and is revolved at a speed synchronized with that of the esses.

United States Patent 3,152,977 RGLL FGR MARKING METAL STRIP George A. Bartholomew, Penn Township, Allegheny County, and Richard F. Higgs, Monroeville, Pa, assig (us to United States Steel Corporation, a corporation of New Jersey Filed Dec. 8, 1960, Ser. No. 74,4% 1 lClairn. (Cl. 204-224} The present invention relates generally to the marking of continuous metal strip and has as its primary object the provision of an improved roll for effecting electrolytic etching of markings on continuous steel strip.

The application of distinctive markings on electrolytic tin plate is necessary for the purpose of identifying the tin plate as to its origin, type, quality, etc. before and after fabricationinto finished products. To be effective it is necessary for such marking to fulfill certain minimum requirements. For example, the marking should not affect lacquerability; the marking should be resistant to subsequent steriliZation processing conditions; and the marking should be durable so that it is detectable on the fabricated tin plate product after at least three years. None of the methods and apparatuses developed for marking tin' plate prior to our invention have been fully satisfactory.

By the apparatus of our invention metal sheet and strip may be processed continuously and controllably by electrolytic means prior to tinning to achieve marking that will be visible after tinning. plish this by continuously etching a predetermined pattern on the surface of rapidly moving metal strip by contacting the traveling strip with a perforated, electrolyte-carrying, electrically charged roll. The roll is covered with a sleeve of plastic or other electrically insulating or non-conductive materialcontaining holes arranged in the pattern to be etched on the strip. Rings of felt Wick material are provided under the insulating sleeve in circumferential grooves spaced axially along the exterior of the roll which communicate with the perforations in the roll face. The felt wick rings carry the electrolyte from the perforations of the roll to the insulating sleeve. The roll is connected in'an electrolytic circuit with a DC. generator, a conductor roll and the strip itself. in this circuit the roll functions as the cath- Thus,

strip, a continuous and repetitive pattern may be electrotrolytically tinned in the usual manner.

Inasmuch as'the marking is etched into thebase metal by our method, it may be made to be visible'without the necessity of removing a subsequently applied tin coating,

or if. desired, it may be made to be invisible until the tin is removed. The marking will not be obliterated by subsequent lacquering of the tin plate or sterilization proc- Since the marking is etched into the base metal it will be visible even after partial corrosion of the base metal has occurred and, therefore, will be visible for many years under normal conditions.

The invention will be fully apparent from the following FIGURE 1 is a schematic elevational view of the entrance end of an electrolytic'tinning line having the mark- FIGURE 2 is an end view looking at the entrance end of an electrolytic tinning line having the marking roll of fthe invention installed therein;

We propose to accom- FIGURE 3 is a longitudinalsectional view of the marking roll of the invention;

FIGURE 4 is a cross-sectional view taken on the line IV-IV of FIGURE 3;

FIGURE 5 is an enlarged detail partial view of FIG- URE 3; and

FIGURE 6 is a cross-sectional view taken on the line VIVI 0f FIGURE 5.

Referring to FIGURES 1 and 2, FIGURE 1 schematically shows the entrance end of an electrolytic tinning line having the markingroll of the invention installed therein. Reference numeral 2 designates the pickling tank of the line which contains a solution of sulphuric acid. A conductor roll 4 is journaled above the tank 2 and a sink roll 6 is rotatably mounted inside the tank.

The marking roll of the invention, designated generally by reference numeral 8, is rotatably mounted above the tank 2 adjacent the conductor roll 4. A pulley 16 may be provided on the shaft of the marking roll whereby detailed disclosure and the appended claim when read inv I connection with the accompanying drawings in which:

the marking roll can be driven by means of a V-belt drive 12 connected to 'a motor (not shown). In operation, strip S to be tinned is passed around the conductor roll 4, into the tank 2, around the sink'roll 6 and then out of the tank 2, around the marking roll 8 and then back into the tank to complete the pickling operation. After leaving the pickling tank the strip is rinsed and then electrolytically tinned in a conventional manner.

The construction just described is conventional except for the novel marking roll 8 of our invention, the details of which will now be described. a

The marking roll 8 comprises a shaft 16 having a hollow cylindrical roll body 18 mounted coaxially thereon. A perforated stiffener plate 19 may be provided on the interior of the roll body 18 welded to its interior wall for purposes of maintaining rigidity of the roll body. A longitudinally extending passageway 29 is provided in one end of shaft 16 having a radially directed opening 22 communicating with the interior of the hollow roll body. The opposite end of shaft 16 is provided with a similar longitudinally extending passageway 24 having a radially directed opening 26 also communicating with the interior of the roll body 18.

The shaft 16 is connected with a piping system 28 by means of rotary joints 30 at each end of the shaft. The piping system 28 includes a feed line 3?. extending from a reservoir tank 3410 the end of the shaft 16 containing passageway 20. A return line 36 of the system 28 extends from the end of the shaft 16 containing the passageway 24. A pump 38 in the feed-line 32 feeds electrolyte in the form of sulphuric acid of approximately 6.5%

by weight concentration from the reservoir tank 34 to 1 the hollow body of the roll by means of passageway 20, outlet opening 22 and the feed line 32 as will be more fully described hereinafter.

The face of the hollow cylindrical roll body 18 is provided with perforations 40 which communicate with the interior of the roll body. External circumferential grooves 42 are formed in the face of the roll body and are spaced axially therealong communicating with the perforations 4% A ring 44 offelt wick material is disposed in each of the grooves 42 for a purpose which will become apparent. V

A perforated sleeve 46 of non-conducting electrically insulating material is disposed around the roll body 18. The sleeve 46 may be made of plastic such as Teflon or similar material. The perforations 47 in the sleeve 46 each communicate with one or the other of the felt Wick rings 44 and are arranged in a predetermined pattern so as to form a particular mark or code.

in operation, electrolyte is pumped from the reservoir 'tank 34 through the feed line 32 and passageway 20 into the hollow roll body 18 where it is temporarily and continuous'ly stored under pressure. Then, when the roll 8 revolves as the strip S is passing thereover a portion of the electrolyte stored in the roll passes through the perforated face of the roll 'body 18 into the circumferential grooves 42 and, by virtue of capillarity, centrifugal force, and hydrostatic pressure, permeates the felt Wick rings 44 and wets the peripheral surfaces thereof. The electrolyte then passes into the perforations 47 of the sleeve 46 which, upon revolution of the roll body 18, continually contacts the surface of strips and etchesit according to the pattern formed by the holesinthe sleeve.

The electrolyte may be causedto fiow intothe roll body continuously or intermittently "as desired. We have foundthat by positioning the marking roll over the pickling'tank that contains acid, the apparatus of the invention can be operated to produce a mark satisfactorily without continuously circulating acid through the marking roll. Satisfactory marking can be achieved even though the acid is not circulated through the marking roll until it is necessary to do so'to clear the holes in the plastic sleeve, for example, after every 24 hours of operation.

The felt wick rings 44 under the non-conductor sleeve 46 do not touch the strip; instead they merely serve as wicks for feeding electrolyte to the holes 47 in the sleeve, which remain 'full of electrolyte (and thus are capable of conducting current) because of capillary action.

An electrolytic circuit for carrying out the method of our invention may 'be providedin a conventional manner such as by passing an electrolytic current from a DC. generator 43 through brushes 50 to a collector ring 52 on the conductor roll 4. The current then passes along the strips into the sulphuric acid solution in the pickling tank 2 and then to the marking roll 8 where electrolysis occurs and the strip surface is etched as it .passes over the holes 4.7 in the sleeve 46,. The current then flows out of the marking roll through a collector ring 54. and brushes 56 attached thereto back to the generator. In the electrolytic circuit just described the strip S is anodic and the marking roll 8 is cathodic. We have obtained good results with the method of our invention using an electrolytic current of approximately 140 to 150 amperes at .94 volts; an electrolyte consisting of an aqueous solution of sulphuric acid containing approximately 6.5%, by weight, sulphuric acid; and a line speed of 600 feet per minute. The acid concentration is not critical. We have obtained good results with aqueous solutions containing from approximately 3% to approximately 8%,

by weight, sulphuric acid. The intensity of the marking may be varied at will by suitable manipulation of the current density and the line speed.

If desired, .the acid in the pickling tank can be used as hollow roll body mounted coaxially on said shaft, said roll body having closed ends and being'perforated around its circumference, said passageway having an inlet opening adjacent one end and an outlet opening adjacent its opposite end, each of said openings communicating with the interior of said body, said roll body having external circumferential grooves spaced axially therealong communicating with the perforations therein, a ring of felt wick material disposed in each of saidgrooves, a perforated sleeve of electrically insulating material around said body, the sleeve perforations being arranged in the pattern of said mark, each of the sleeve perforations communicating with one of said rings of felt wick material whereby electrolyte is conducted from said rings to said metal strip in traveling contact with the roll, the circumferential area of said roll body between said grooves being free of felt wick material and in direct cont-act with the inner surface of said sleeve whereby a bond is created between said sleeve and said roll body.

References Cited in the file of this patent UNITED STATES PATENTS 2,080,234 Schlotter May 11, 1937 2,266,347 Watson Dec. 16, 1941 2,498,124 Lindsay Feb. 21, 1950 2,498,129 Lindsay Feb. 21, 1950 2,540,602 Thomas et a1 :Feb. 6, 1951 2,689,215 Bart Sept. 14, 1954 2,798,849 Lindsay July 9, 1957 2,833,702 El-fers May 6, 1958 2,921,893 Smith Jan. 19, 1960 2,924,563 Gray Feb. 9, 1960 2,848,401 Hartley Aug. 19, 1960 2,967,813 Lindsay Jan. 10, 1961 FOREIGN PATENTS 176,064 Great Britain Mar. 3, 1922 400,510 Great Britain Oct. 26, 1933 483,503 Great Britain Apr. 21, 1938 457,040 Canada May 31, 1949 

